87' pickup GM 350 crate swap, won't start

[Plowman]

Hello

I'm going. It's trying to get my truck started and I'm hoping someone here can help me.

The truck is an 87' GMC V1500, it came with a 305 and a 700R4 from the factory. The 305 had a catostrophic failure and needed to be replaced. It was running fine until it had a bearing issue and started knocking.

So I picked up a GM crate 350, new injectors, knock sensor, and ESC module.

At first I had issues getting to to fire and determined it was 180 degrees out of alignment. That was fixed and the backfiring stopped. At this point it would start to fire, but It would not catch and run. I insured cylinder one was a tdc and have checked the wires multiple times. I have tried to adjust the timing a little and it sounds like it wants to start but just won't.

Since then I have replaced the fuel pump , pump relay, and fuel filter (although I can see fuel coming out of the injectors, and hear the pump priming when I turn the ignition on). I have also ordered a pressure gauge and fitting for the filter to confirm actual fuel pressure.

I have also replaced the entire distributor with a new AC Delco oem replacement. The old one was rather rusted and the contact didn't seem great. I was concerned the pickup or sensor was bad and not sending the injector pulses.

This didn't seem to have any effect so I ordered myself a code reader to see if I could pull any helpful info off the computer to help get me on the right track. Unfortunately it spit out 10 codes at me and did nothing to help me narrow down my issue.

The code reader gave the the following codes.

42
35
33
32
31
55
54
52
51
43

After seeing these the ECM seemed to be a fairly common thing amongst the codes. I double checked my grounds and decided to order a replacement AC delco oem ECM. After putting the prom and memcal in the new ECM I checked the grounding and wiring one last time before hooking the battery back up.

The truck is a plow truck and the previous owner did the install and hacked the wiring up a little. Befor hooking the battery back up
I noticed I had been hooking a grounding cable directly to the positive terminal (the truck has a standard neg cable terminal and multiple additional
Wires on a threaded negative terminal, with only three wires on the threaded terminal on the positive side and no standard battery cable terminal). It has a brand new marine/rv battery.

I corrected the incorrect ground cable routing prior to trying to start on the new ECM. The truck did the same thing and seemed to throw out the same exact ten error codes afterwards.

There are multiple other supporting features nf items that were cleaned and or replaced but nothing that I can think of that would cause this. Has a new radiator and water pump, torque converter, an edelbrock manifold, I cleaned the tbi unit and rebuilt the fpr. I have a new set of headers but have reinstalled the factory manifolds and am trying to start it open header with the factory 02 sensor installed. All of the factory smog equipment was retained.

I don't know what I am missing.

 

[Stinky]

A motor needs 3 things to run...spark, gas, compression.

Do the valves come adjusted? Do you fool w/them? If so, back them off 1 full turn and go from there.

Verify that you have spark. i'd probably do that 1st...if no spark, then find out why not. Then, either turn your dizzy, more than a little bit, and see if it will fire. Are you sure the timing is right? The dizzy will go in 8 dif ways....yes eight, not 2. Pull the valve cover that has the 5th Cly in the firing order (I think that it is #6), turn the crank, when the mark comes up on your desired setting (about 10 btdc) then set it there. The rockers on #6 should be moving (assuming that it is the 5th cyl), the exhaust should be about done and the intake starting. So, when the rockers are moving on the cyl 1 rotation after #1, in the firing order, that indicates that #1 is @ tdc comprsson. Then, w/the mark set, set the dizzy w/the rotor pointing @ where the #1 cyl's sparkplug post, or slowly turn the dizzy CCW until you get at the almost exact spot where you get a spark on #1. You'll have to turn it back and forth several times in order to get it right. You'll be able to get it real close, more than close enough, either way that you decide how to do it.

Dump some gas in the tbi, half a cup is plenty...if you are short on gas, you should be able to get it to fire. After I verified that I have spark, I'd do this before fooling w/the timing (quick and simple to see if you are short on gas).

Btw, until it runs...I don't trust your new dizzy. But if you do the above, and your spark seems right, then you are probably ok....

If you did not fool w/the valves, then you either do not have the CORRECT spark, or gas...plain and simple.

 

[Plowman]

The motor came assembled from pan to valve covers and I have not taken them off. I assume there was an initial cold lash done but I'm not sure if these motors are broke in at all. It is a GM crate engine.

I have verified I have spark at the coil and at the #1 plug wire.

I had the distributor off 180 deg at first but have adjusted it since. I have a mark on the manifold where the #1 post originally pointed towards. I have the distributor inserted so that when fully seated in the oil pump my number one post is on the mark and the rotor is pointing at my #1 post.

I have been using the notch on the balancer to align #1 at tdc befor dropping the dizzy in.

So although I haven't popped the valve covers off, or been using the finger over spark plug method (which seems like it could be inprecise). I think the timing should be close enough to start.

I have spun it at least half way each way between the next posts, and even took all the wires off and pushed them over a spot so I could spin it further forward because the plugs were starting to hit the firewall.

I feel like it is electrical since it will fire but not stay running. But obviously I don't know what is wrong so all I put is welcome

The next thing on my list to check currently is fuel pressure but I am waiting on the fuel filter adapter. So maybe double checking the timing mark on the balancer and insuring cyl 1 is infact tdc should be on the list.

 

[handloader90]

Battery may not have enough juice to fire it up.

I had a battery that would read 12v, would crank all day but wouldn't start an engine after the swap... couldn't figure out what it could be.

Put a battery that I knew was good in and woke the neighbors up.

Engine to frame and engine to body grounds are important too.

 

[Bent77]

TBI, and it tried to fire at first?

Unplug the battery and charge it.

Once its good, Then reset the timing to 0° with the disconnect on the firewall unhooked. Shut it off before you reconnect it

 

[Plowman]

TBI, and it tried to fire at first?

Unplug the battery and charge it.

Once its good, Then reset the timing to 0° with the disconnect on the firewall unhooked. Shut it off before you reconnect it

It is a 350 tbi yes with the flat tappit valvetrain. It needs to crank a few times then it will fire once and just die.

The battery is brand new like a few months old, it was replaced during this process. But I will get it on a charger since it isn't doing much now.

When you say disconnect on the firewall are you talking the plugs on the backside of the distributor (firewall side). Not the fuel pump relay or something else physically on the firewall? Then reconnect once I get the crank back to tdc on cyl 1 and confirm the distributor is still pointing at the number one post?

And when you say shut it off befor you reconnect are you referring to the battery charger? You didn't really say anything about turning anything else on.

 

[Bent77]

It is a 350 tbi yes with the flat tappit valvetrain. It needs to crank a few times then it will fire once and just die.

The battery is brand new like a few months old, it was replaced during this process. But I will get it on a charger since it isn't doing much now.

When you say disconnect on the firewall are you talking the plugs on the backside of the distributor (firewall side). Not the fuel pump relay or something else physically on the firewall? Then reconnect once I get the crank back to tdc on cyl 1 and confirm the distributor is still pointing at the number one post?

And when you say shut it off befor you reconnect are you referring to the battery charger? You didn't really say anything about turning anything else on.

There is a brown or grey wire (depending on your harness) this has to be unplugged to set the timing on a TBI, or it makes the ECM mad

Engine off, unplug this wire. Has an actual disconnect in the middle of the wire on the firewall. Then start it. 0* tighten the dizzy.
Then shut the engine off, then reconnect this wire

The ECM will take care of all of the timing for you.

Start there before we track down any other issues.

 

[Plowman]

There is a brown or grey wire (depending on your harness) this has to be unplugged to set the timing on a TBI, or it makes the ECM mad

Engine off, unplug this wire. Has an actual disconnect in the middle of the wire on the firewall. Then start it. 0* tighten the dizzy.
Then shut the engine off, then reconnect this wire

The ECM will take care of all of the timing for you.

Start there before we track down any other issues.

There is a single wire that comes Out of the loom shortly after the harness comes through the firewall near the brake booster. It appears to be brown in color with a grey or black strip on it. It has a connector in the middle of the wire then feeds back in to the main harness loom. Could this be it?

 

[Bent77]

There is a single wire that comes Out of the loom shortly after the harness comes through the firewall near the brake booster. It appears to be brown in color with a grey or black strip on it. It has a connector in the middle of the wire then feeds back in to the main harness loom. Could this be it?

Should be

 

[1-ton]

One thing you had better be real carefull with is spending too much time cranking and cranking the engine trying to get it to start. This could flatten your cam lobes and kill the engine. When you are starting up a flat tappet camed engine for the first time everything needs to be installed correctly, in order to start up the engine immediately and bring up to 2000 RPM for at least 20 minutes to properly break in the cam.

 

[frankin5]

Did you put a new balancer on for a 350 or did you reuse the 305 balancer

 

[Plowman]

Did you put a new balancer on for a 350 or did you reuse the 305 balancer

The motor came with a new balancer, I just installed the original crank pulley, fresh belts, and original accessories.

I bought an oil pump priming tool and I have been using that to oil things up when I first got it together and have been using it each time I pull the dizzy out to try and keep the valvetrain nice and lubed. I am also using comp cans break in oil from flat tappet motors and some of the Lucas break in additive.

 

[ktmoutfront]

I will ask a basic question. Does it run only while you are cranking it. Let off the starter and it dies?

 

[Plowman]

I will ask a basic question. Does it run only while you are cranking it. Let off the starter and it dies?

Even if I stay on the starter and crank it it won't run. Just gives a first pop like it wants to start then dies off.

 

[ktmoutfront]

Even if I stay on the starter and crank it it won't run. Just gives a first pop like it wants to start then dies off.

Never mind then.

 

[Plowman]

So a little update.

After checking fuel pressure it was showing that as I turned the ignition on and cranked the fuel pressure would climb then immediately fall off.

I have double checked the lines and replaced the pump again.

When I jump the pump from the relay I can hear a missing sound coming from the tb. I can't tell if it is air coming in or leaking out but there doesn't seem to be fuel leaking anywhere..

It sounds like I can hear fuel running back in to the tank which I assume is the return line doings it's job.

I am assuming at this point that there are one of two things happening.

1. I did something wrong when rebuilding the pressure regulator, and installing the new diaphragm. now somehow it is not regulating pressure correctly and is not giving my injectors the proper pressure.

2. I am slightly skeptical that the hardline on the sender unit in the tank is cracking inside the tank where it meets the cap and the fuel pressure is leaking there and draining back in to the tank.

What do you guys think? Any recommendations on the next step?

 

[Bent77]

So a little update.

After checking fuel pressure it was showing that as I turned the ignition on and cranked the fuel pressure would climb then immediately fall off.

I have double checked the lines and replaced the pump again.

When I jump the pump from the relay I can hear a missing sound coming from the tb. I can't tell if it is air coming in or leaking out but there doesn't seem to be fuel leaking anywhere..

It sounds like I can hear fuel running back in to the tank which I assume is the return line doings it's job.

I am assuming at this point that there are one of two things happening.

1. I did something wrong when rebuilding the pressure regulator, and installing the new diaphragm. now somehow it is not regulating pressure correctly and is not giving my injectors the proper pressure.

2. I am slightly skeptical that the hardline on the sender unit in the tank is cracking inside the tank where it meets the cap and the fuel pressure is leaking there and draining back in to the tank.

What do you guys think? Any recommendations on the next step?

1- on low pressure it should still run
2- if the hard line was cracked, it should witness a low/no pressure condition all the time

Is there power through the oil safety switch after it meets oil pressure?

 

[Plowman]

1- on low pressure it should still run

It doesn't really have low pressure. When I hit the power to the pump it seemed to spike up at first then immediately fall off and was unable to hold pressure. Could this be the regulator?

I replaced the spring and diamphram in the regulator and I thought I had it in there ok. I can't see any wrinkles in the diamphram along the outer seal, but maybe the spring isn't seated correctly or something?

I really can't understand the hissing sound from the tb when I jump the fuel pump. I would think A leak in the system would cause fuel to be pushed out somewhere. Not what sounds to be an air or vacume leak?

Is there power through the oil safety switch after it meets oil pressure?

I don't quite understand your question. Are you talking about the oil pressure sender, on the back of the motor?

 

[Bent77]

Yep that sender. Just wanted to make sure that switch closes, as that powers the fuel pump after it starts

You might check that before seeing that the regulator is okay

 

[midnitewarya]

When I did my swap last year, I had this exact same problem. I rebuilt the TBI, just like you, with new injectors. For some reason, the new injectors wouldn't squirt correctly. I did everything you are doing until I finally had someone crank it while I watched the injectors work. They were spraying sporadically and shutting off intermittently. I thought I had bad injectors...

I disconnected the harness from the injectors and smacked the top of them a few times with a large screwdriver. Reconnected everything and it fired right up.